Soot Dispersants and Lubricating Oil Compositions Containing Same

ABSTRACT

Linked aromatic compounds found to act as potent soot dispersants in lubricating oil compositions; lubricating oil compositions containing such soot dispersants and precursor compounds from which the soot dispersants are derived.

FIELD OF THE INVENTION

This invention relates to a novel class of linked aromatic compoundsthat act as potent soot dispersants in lubricating oil compositions andlubricating oil compositions containing same. More specifically, theinvention is directed to compounds that, when added to lubricating oilcompositions provide soot dispersing performance in the industrystandard “Mack T11” engine test, with reduced levels of additivenitrogen. The invention is further directed to a novel class ofprecursor compounds from which such soot dispersants can be derived.

BACKGROUND OF THE INVENTION

Global Heavy Duty Diesel (HDD) engine emission legislation requiresstepwise reductions in NO and particulate emissions between 1989 and2009. Many diesel engine manufacturers are now incorporating into HDDengines an Exhaust Gas Recirculation (EGR) system that is operated in acondensing mode for at least a portion of the time the engine isoperated (e.g., at least 10% of the time the engine is operated), andretarding engine timing to reduce NO_(x) and particulate emissions. Inengines provided with a cooled EGR system, the EGR stream is cooledbelow the dew point of NO_(x) and SO_(x) and injected back into theengine under positive pressure. Under such conditions, water vaporcondenses with the NO_(x) and SO_(x) to produce high levels of nitricand sulfuric acids in the recirculated exhaust gas stream. Under suchconditions, unacceptable increases in the kinematic viscosity (kv) oflubricating oil compositions have been observed, even in the presence ofrelatively low levels of soot (e.g., 3 mass % soot).

Lubricating oil compositions comprise a major amount of base oil andadditives that improve the performance and increase the useful life ofthe lubricant. Nitrogen-containing dispersants are commonly usedlubricant additives. The function of a dispersant is to maintain insuspension within the oil, insoluble materials formed by oxidation andother mechanisms during use of the oil, to prevent sludge flocculationand precipitation of the insoluble materials. Another function of thedispersant is to reduce the agglomeration of soot particles, thusreducing increases in the viscosity of the lubricating oil upon use. Inthe severe environment of an engine provided with a cooled EGR system,it has been found that soot induced viscosity increase, as measured in a“Mack T-11” test cannot be controlled by conventional dispersants, evenwhen the amount of such conventional dispersants are increased.Therefore, compounds providing potent soot dispersing properties andcrankcase lubricants providing improved soot dispersing performance,have been continuously demanded.

U.S. Pat. No. 1,815,022 to Davis (1931) discloses condensates ofnaphthalene and essentially linear chlorinated waxes formed by FreidelCraft alkylation of the naphthalene. Such compounds are described asfunctioning as wax crystal modifiers or lube oil flow improver (LOFT)additives and were added to oil to improve the cold flow characteristicsthereof. These compounds have not been used for a number of years and,due to the high chlorine content, these compounds would be consideredunsuitable for use in a modern passenger car, or heavy duty diesel motoroil formulations. In modern formulations, these compounds have beensupplanted by fumarate/vinyl acetate copolymers orpolymethacrylate-based LOFIs.

U.S. Pat. No. 4,708,809 to Davis describes a lubricating oil compositioncontaining a phenolic compound of the formula:

(R)_(a)—Ar—(OH)_(b)

wherein R is a saturated hydrocarbon group having 10 or more aliphaticcarbon atoms; a and b are each independently 1 to 3 times the number ofaromatic nuclei present in Ar; and Ar is a single, fused or linkedpolynuclear ring moiety that is optionally substituted. It is allegedthat the addition of a minor amount of such a compound to a lubricantcomposition that is mixed with fuel will lead to a reduction in pistonring sticking in a two cycle engine.

U.S. Pat. No. 6,495,496 to Gutierrez et al. describesnitrogen-containing low molecular weight Mannich base condensates ofhydroxy aromatic compounds, an aldehyde and an amine that are useful assoot dispersants in lubricating oils.

U.S. Pat. No. 6,750,183 to Gutierrez et al. discloses certain oligomersuseful as soot dispersants, which oligomers are defined by the formula:

wherein each Ar independently represents an aromatic moiety optionallysubstituted by 1 to 6 substituents selected from H, —OR₁, —N(R₁)₂, F,Cl, Br, I, -(L-(Ar)-T), —S(O)_(w)R₁, —(CZ)_(x)—(Z)_(y)—R₁ and—(Z)_(y)—(CZ)_(x)—R₁, wherein w is 0 to 3, each Z is independently O,—N(R₁)₂ or S, x and y are independently 0 or 1 and each R₁ isindependently H or a linear or branched, saturated or unsaturated,optionally substituted, hydrocarbyl group having from 1 to about 200carbon atoms; each L is independently a linking moiety comprising acarbon-carbon single bond or a linking group; each T is independently H,OR₁, N(R₁)₂, F, Cl, Br, I, S(O)_(w)R₁, (CZ)_(z)—(Z)_(y)—R₁ or(Z)_(y)—(CZ)_(x)—R₁, wherein R₁, w, x, y and Z are as defined above; andn is 2 to about 1000.

U.S. Published Patent Application 2006/0189492 A1 to Bera et al.discloses certain reaction products of acylating agents and oligomershaving the following structures:

where each Ar independently represents an aromatic moiety having 0 to 3substituents selected from alkyl, alkoxy, alkoxyalkyl, hydroxy,hydroxyalkyl, halo and combinations thereof; each L is independently alinking moiety comprising a carbon-carbon single bond or a linkinggroup; each Y is independently a moiety of the formulaH(O(CR₂)_(n))_(y)X—, where X is selected from (CR′₂)_(z), O and S; R andR′ are each independently selected from H, C₁ to C₆ alkyl and aryl; z is1 to 10; n is 0 to 10 when X is (CR′₂)_(z), and 2 to 10 when X is O orS; and y is 1 to 30; each a is independently 0 to 3; at least one Armoiety bears at least one group Y; and m is 1 to 100; and

where each Ar independently represents an aromatic moiety having 0 to 3substituents selected from alkyl, alkoxy, alkoxyalkyl, hydroxy,hydroxyalkyl, acyloxy, acyloxyalkyl, aryloxy, aryloxy alkyl, halo andcombinations thereof; each L is independently a linking moietycomprising a carbon-carbon single bond or a linking group; each Y′ isindependently a moiety of the formula Z(O(CR₂)_(n))_(y)X—, where X isselected from (CR′₂)_(z), O and S; R and R′ are each independentlyselected from H, C₁ to C₆ alkyl and aryl; z is 1 to 10; n is 0 to 10when X is (CR′₂)_(z), and 2 to 10 when X is O or S; y is 1 to 30; Z isH, an acyl group, an alkyl group or an aryl group; each a isindependently 0 to 3, at least one Ar moiety bears at least one group Yin which Z is not H; and m is 1 to 100. Compounds of latter formula aredescribed as useful soot dispersants.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there isprovided a class of novel linked aromatic compounds found to act aspotent soot dispersants in lubricating oil compositions.

In accordance with a second aspect of the invention, there are providedlubricating oil compositions containing the novel compounds of the firstaspect, which lubricating oil compositions are capable of providingexcellent soot dispersing performance.

In accordance with a third aspect of the invention, there is provided amethod of operating a compression ignited (diesel) engine equipped withan EGR system, which method includes the steps of lubricating thecrankcase of such an engine with a lubricating oil composition of thesecond aspect, and operating the engine.

In accordance with a fourth aspect, there is provided a novel class ofprecursor compounds from which the compounds of the first aspect can bederived.

DETAILED DESCRIPTION OF THE INVENTION

Compounds useful as precursors from which the soot dispersants of thepresent invention can be derived can be defined by the formula:

wherein each Ar independently represents an aromatic moiety having 0 to3 substituents selected from the group consisting of alkyl, alkoxy,alkoxyalkyl, aryloxy, aryloxyalkyl, hydroxy, hydroxyalkyl, halo andcombinations thereof; each L is independently a linking moietycomprising a carbon-carbon single bond or a linking group; each Y isindependently —OR″ or a moiety of the formula H(O(CR₂)_(n))_(y)X—,wherein X is selected from the group consisting of (CR′₂)_(z), O and S;R and R′ are each independently selected from H, C₁ to C₆ alkyl andaryl; R″ is selected from C₁ to C₁₀₀ alkyl and aryl; z is Ito 10; n is 0to 10 when X is (CR′₂)_(z), and 2 to 10 when X is O or S; and y is 1 to30; each a is independently 0 to 3, with the proviso that at least oneAr moiety bears at least one group Y; and m is 1 to 100.

Aromatic moieties Ar of Formula I can be a mononuclear carbocyclicmoiety (phenyl) or a polynuclear carbocyclic moiety. Polynuclearcarbocyclic moieties may comprise two or more fused rings, each ringhaving 4 to 10 carbon atoms (e.g., naphthalene) or may be linkedmononuclear aromatic moieties, such as biphenyl, or may comprise linked,fused rings (e.g., binaphthyl). Examples of suitable polynuclearcarbocyclic aromatic moieties include naphthalene, anthracene,phenanthrene, cyclopentenophenanthrene, benzanthracene,dibenzanthracene, chrysene, pyrene, benzpyrene and coronene and dimer,trimer and higher polymers thereof. Ar can also represent a mono- orpolynuclear heterocyclic moiety. Heterocyclic moieties Ar include thosecomprising one or more rings each containing 4 to 10 atoms, includingone or more hetero atoms selected from N, O and S. Examples of suitablemonocyclic heterocyclic aromatic moieties include pyrrole, furan,thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidineand purine. Suitable polynuclear heterocyclic moieties Ar include, forexample, quinoline, isoquinoline, carbazole, dipyridyl, cinnoline,phthalazine, quinazoline, quinoxaline and phenanthroline. Each aromaticmoiety (Ar) may be independently selected such that all moieties Ar arethe same or different. Polycyclic carbocyclic aromatic moieties arepreferred. Most preferred are compounds of Formula I wherein each Ar isnaphthalene. Each aromatic moiety Ar may independently be unsubstitutedor substituted with 1 to 3 substituents selected from alkyl, alkoxyalkoxyalkyl, hydroxyl, hydroxyalkyl, halo, and combinations thereof.Preferably, each Ar is unsubstituted (except for group(s) Y and terminalgroups).

Each linking group (L) may be the same or different, and can be a carbonto carbon single bond between the carbon atoms of adjacent moieties Ar,or a linking group. Suitable linking groups include alkylene linkages,ether linkages, diacyl linkages, ether-acyl linkages, amino linkages,amido linkages, carbamido linkages, urethane linkages, and sulfurlinkage. Preferred linking groups are alkylene linkages such as—CH₃CHC(CH₃)₂—, or C(CH₃)₂—; diacyl linkages such as —COCO— or—CO(CH₂)₄CO—; and sulfur linkages, such as —S₁— or —S_(x)—. Morepreferred linking groups are alkylene linkages, most preferably —CH₂—.

Preferably, Ar of Formula (I) represents naphthalene. Preferably, fromabout 2% to about 98% of the Y units are H(O(CR₂)₂)_(y)O—, wherein y is1 to 6, and from about 98% to 2% of Y units are —OR″. More preferably,from about 2% to about 98% of Y units are HOCH₂CH₂O—, and from about 60%to 10% of Y units are —OCH₃; and L is CH₂. In one particularly preferredembodiment, Ar represents naphthalene, from about 40% to about 90% suchas from about 65 mol. % to about 75 mol. % of Y units are HOCH₂CH₂O—,and from about 60% to 10%, such as from about 35 mol. % to about 25 mol.% of Y units are —OCH₃, and L is CH₂. Preferably, compounds of Formula(I) are derived from about 65 mol. % to about 75 mol. % of2-(2-naphthoxy)-ethanol and from about 35 mol. % to about 25 mol. % of2-methoxy naphthalene, wherein m is 1 to about 25.

Methods for forming compounds of Formula I should be apparent to thoseskilled in the art. A hydroxyl aromatic compound, such as naphthol canbe reacted with an alkylene carbonate (e.g., ethylene carbonate) toprovide a compound of the formula AR—(Y)_(a). Preferably, the hydroxylaromatic compound and alkylene carbonate are reacted in the presence ofa base catalyst, such as aqueous sodium hydroxide, and at a temperatureof from about 25 to about 300° C., preferably at a temperature of fromabout 50 to about 200° C. During the reaction, water may be removed fromthe reaction mixture by azeotropic distillation or other conventionalmeans. If separation of the resulting intermediate product is desired,upon completion of the reaction (indicated by the cessation of CO₂evolution), the reaction product can be collected, and cooled tosolidify. Alternatively, a hydroxyl aromatic compound, such as naphthol,can be reacted with an epoxide, such as ethylene oxide, propylene oxide,butylenes oxide or styrene oxide, under similar conditions toincorporate one or more oxy-alkylene groups.

To form a compound of Formula I, the resulting intermediate compoundAr—(Y)_(a) may be further reacted with a polyhalogenated (preferablydihalogenated) hydrocarbon (e.g., 1-4-dichlorobutane,2,2-dichloropropane, etc.), or a di- or poly-olefin (e.g., butadiene,isoprene, divinylbenzene, 1,4-hexadiene, 1,5-hexadiene, etc.) to yield acompound of Formula I having an alkylene linking groups. Reaction ofmoieties Ar—(Y)_(a) and a ketone or aldehyde (e.g., formaldehyde,acetone, benzophenone, acetophenone, etc.) provides an alkylene linkedcompound. An acyl-linked compound can be formed by reacting moietiesAr—(Y)_(a) with a diacid or anhydride (e.g., oxalic acid, malonic acid,succinic acid, glutaric acid, adipic acid, succinic anhydride, etc.).Sulfide, polysulfide, sulfinyl and sulfonyl linkages may be provided byreaction of the moieties Ar—(Y)_(a) with a suitable difunctionalsulfurizing agent (e.g., sulfur monochloride, sulfur dichloride, thionylchloride (SOCl₂), sulfuryl chloride (SO₂Cl₂), etc.). To provide acompound of Formula I with an alkylene ether linkage, moietiesAr—(Y)_(a) can be reacted with a divinylether. Compounds of Formula I,wherein L is a direct carbon to carbon link, may be formed via oxidativecoupling polymerization using a mixture of aluminum chloride and cuprouschloride, as described, for example, by P. Kovacic, et al., J. PolymerScience: Polymer Chem. Ed., 21, 457 (1983). Alternatively, suchcompounds may be formed by reacting moieties Ar—(Y)_(a) and an alkalimetal as described, for example, in “Catalytic Benzene Coupling onCaesium/Nanoporous Carbon Catalysts”, M. G. Stevens, K. M. Sellers, S.Subramoney and H. C. Foley, Chemical Communications, 2679-2680 (1988).

To form the preferred compounds of Formula (I), having an alkylenelinking group, more preferably a methylene linking group, base remainingin the Ar—(Y)_(a) reaction mixture can be neutralized with acid,preferably with an excess of acid (e.g., a sulfonic acid) and reactedwith an aldehyde, preferably formaldehyde, and preferably in thepresence of residual acid, to provide an alkylene, preferably methylenebridged compound of Formula (I). The degree of polymerization of thecompounds of Formula I range from 2 to about 101 (corresponding to avalue of m of from 1 to about 100), preferably from about 2 to about 50,most preferably from about 2 to about 25.

To provide the preferred compounds of Formula (I), naphthyloxyethanoland 2-methoxylnaphthalene can be reacted with formaldehyde in thepresence of an acid catalyst, preferably selected from oil solublesulfonic acid and solid acid catalyst. Preferably, the naphthoxyethanolis the product of a reaction of a hydroxyl-naphthylene compound in thepresence of a base catalyst. Preferably, remaining base is neutralizedwith an excess of acid prior to the introduction of the formaldehyde.

Compounds of the present invention useful as the soot dispersants can beformed by reacting a compound of Formula (I) with at least one of anacylating agent, an alkylating agent and an arylating agent, and arerepresented by the formula:

wherein:each Ar independently represents an aromatic moiety having 0 to 3substituents selected from the group consisting of alkyl, alkoxy,alkoxyalkyl, hydroxy, hydroxyalkyl, acyloxy, acyloxyalkyl,acyloxyalkoxy, aryloxy, aryloxyalkyl, aryloxyalkoxy, halo andcombinations thereof; each L is independently a linking moietycomprising a carbon-carbon single bond or a linking group; each Y′ isindependently a moiety of the formula Z′O— or Z(O(CR₂)_(n))_(y)X—,wherein X is selected from the group consisting of (CR′₂)_(z), O and S;R and R′ are each independently selected from H, C₁ to C₆ alkyl andaryl; z is 1 to 10; n is 0 to 10 when X is (CR′₂)_(z), and 2 to 10 whenX is O or S; y is 1 to 30; Z is H, an acyl group, a polyacyl group, alactone ester group, and acid ester group, an alkyl group or an arylgroup; Z′ is selected from C₁ to C₁₀₀ alkyl and aryl; each a isindependently 0 to 3, with the proviso that at least one Ar moiety bearsat least one group Z(O(CR₂)_(n))_(y)X— in which Z is not H; and m is 1to 100.

Suitable acylating agents include hydrocarbyl carbonic acid, hydrocarbylcarbonic acid halides, hydrocarbyl sulfonic acid and hydrocarbylsulfonic acid halides, hydrocarbyl phosphoric acid and hydrocarbylphosphoric halides, hydrocarbyl isocyanates and hydrocarbyl succinicacylating agents. Preferred acylating agents include polyacylatingagents which provide bis ester, ester acid and/or ester lactonesubstituent groups. Preferred acylating agents are C₈ and higherhydrocarbyl isocyanates, such as dodecyl isocyanate and hexadodecylisocyanate and C₈ or higher hydrocarbyl acylating agents, morepreferably polybutenyl succinic acylating agents such as polybutenyl, orpolyisobutenyl succinic anhydride (PIBSA). Preferably the hydrocarbylsuccinic acylating agent will be derived from polyalkene having a numberaverage molecular weight ( Mn) of from about 100 to 5000, preferablyfrom about 200 to about 3000, more preferably from about 450 to about2500. Preferred hydrocarbyl isocyanate acylating agent will be derivedfrom polyalkene having a number average molecular weight ( Mn) of fromabout 100 to 5000, preferably from about 200 to about 3000, morepreferably from about 200 to about 2000. Acylating agents can beprepared by conventional methods known to those skilled in the art, suchas chlorine-assisted, thermal and radical grafting methods. Theacylating agents can be mono- or polyfunctional. Preferably, theacylating agents have a functionality of less than 1.3, wherefunctionality (F) is be determined according to the following formula:

F=(SAP× Mn)/((112,200×A.I)−(SAP×MW))

wherein SAP is the saponification number (i.e., the number of milligramsof KOH consumed in the complete neutralization of the acid groups in onegram of the acyl group-containing reaction product, as determinedaccording to ASTM D94); Mn is the number average molecular weight of thestarting polyalkene; A.I. is the percent active ingredient of the acylgroup-containing reaction product (the remainder being unreactedpolyalkene, acylating agent and diluent); and MW is the molecular weightof the acyl group (e.g., 98 for succinic anhydride). Acylating agentsare used in the manufacture of dispersants, and a more detaileddescription of methods for forming acylating agents is described in thedescription of suitable dispersants, presented infra. Suitablealkylating agents include C₈ to C₃₀ alkane alcohols, preferably C₈ toC₁₈ alkane alcohols. Suitable arylating agents include C₈ to C₃₀,preferably C₈ to C₁₈ alkane-substituted aryl mono- or polyhydroxide.

Molar amounts of the compound of Formula (I) and the acylating,alkylating and/or arylating agent can be adjusted such that all, or onlya portion, such as 25% or more, 50% or more or 75% or more of groups Yare converted to groups Y′. In the case where the compound of Formula(I) has hydroxy and/or alkyl hydroxy substituents, and such compoundsare reacted with an acylating group, it is possible that all or aportion of such hydroxy and/or alkylhydroxy substituents will beconverted to acyloxy or acyloxy alkyl groups. In the case where thecompound of Formula (I) has hydroxy and/or alkyl hydroxy substituents,and such compounds are reacted with an arylating group, it is possiblethat all or a portion of such hydroxy and/or alkylhydroxy substituentswill be converted to aryloxy or aryloxy alkyl groups. Therefore,compounds of Formula (II) substituted with acyloxy, acyloxy alkyl,aryloxy and/or aryloxy alkyl groups are considered within the scope ofthe present invention. A salt form of compounds of Formula (II) in whichZ is an acylating group, which salts result from neutralization withbase (as may occur, for example, due to interaction with a metaldetergent, either in an additive package or a formulated lubricant), isalso considered to be within the scope of the invention.

One preferred class of compounds of Formula (II) includes compounds ofFormula (III):

wherein one or more Y′ are groups Z(O(CR₂)_(n))_(y)X— in which Z isderived from lactone ester of formula IV, acid ester of formula V, or acombination thereof;

wherein R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are independently selected from H,alkyl and polyalkyl and polyalkenyl containing up to 200 C; and Z″ isbisacyl of formula VI;

wherein R⁸ and R⁹ are independently selected from H, alkyl and polyalkyland polyalkenyl containing up to 300 C; m is 0 to 100; and p and s areeach independently about 0 to about 25, with the proviso that p≦m; s≦m;and p+s≧1.

Preferred compounds of Formula (III) are those wherein from about 2% toabout 98% of the Y′ units are Z(O(CR₂)₂)_(y)O—, wherein Z is an acylgroup and y is 1 to 6, and from about 98% to 2% of Y′ units are —OR″,such as compounds of Formula (III) wherein Ar is naphthalene; from about2% to about 98% of Y′ units are ZOCH₂CH₂O—, from about 98% to 2% of Y′units are —OCH₃; and L is CH₂. Particularly preferred are compounds ofFormula (III) wherein Ar is naphthalene; from about 40% to about 60% ofY′ units are ZOCH₂CH₂O—, and from about 60% to 40% of Y′ units are—OCH₃; m is from about 2 to about 25; p is from 1 to about 10; and s isfrom about 1 to about 10. Preferably, group Z of Formula (III) isderived from a polyalkyl or polyalkenyl succinic acylating agent, whichis derived from polyalkene having Mn of from about 100 to about 5000, ora hydrocarbyl isocyanate.

Compounds of Formula (II) can be derived from the precursors of Formula(I) by reacting the precursors of Formula (I) with the acylating agent,preferably in the presence of a liquid acid catalyst, such as sulfonicacid, e.g., dodecyl benzene sulfonic acid, paratoluene sulfonic acid orpolyphosphoric acid or a solid acid catalyst such as Amberlyst-15,Amberlyst-36, zeolites, mineral acid clay or tungsten polyphosphoricacid; at a temperature of from about 0 to about 300° C., preferably fromabout 50 to about 250° C. Under the above conditions, the preferredpolybutenyl succinic acylating agents can form diesters, acid esters orlactone esters with the compound of Formula (I).

Compounds of Formula (II) can be derived from the precursors of Formula(I) by reacting the precursors of Formula (I) with the alkylating agentor arylating agent, preferably in the presence of triphenylphosphine anddiethyl azodicarboxylate (DEAD), a liquid acid catalyst, such assulfonic acid, e.g., dodecyl benzene sulfonic acid, paratoluene sulfonicacid or polyphosphoric acid or a solid acid catalyst such asAmberlyst-15, Amberlyst-36, zeolites, mineral acid clay or tungstenpolyphosphoric acid; at a temperature of from about 0 to about 300° C.,preferably from about 50 to about 250° C.

In one preferred embodiment, compounds of Formula (II) are the reactionproduct of a mixture of methylene-bridged naphthoxyethanol and 2-methoxynaphthalene compounds, and an acylating agent selected from polyalkylsuccinic acylating agent and polyalkenyl succinic acylating agent,preferably derived from polybutene having Mn of from about 300 to about5000, preferably in the presence of an acid catalyst (preferably an oilsoluble liquid acid catalyst or a solid acid catalyst). Preferably, theratio of total moles of succinic acylating moieties to total moles ofnaphthyl moieties is from about 1.10 to about 0.5. Preferably, themethylene-bridged naphthoxyethanol and 2-methoxy naphthalene compoundsare the product of a process in which (i) a hydroxyl-naphthylenecompound and ethylene carbonate are reacted in the presence of a basecatalyst to form naphthoxyethanol; (ii) the base is neutralized with anexcess of acid to provide an intermediate; and (iii) the intermediate isreacted with 2-methoxy naphthalene and formaldehyde in the presence ofresidual acid.

Lubricating oil compositions of the present invention comprise a majoramount of an oil of lubricating viscosity and a minor amount of a sootdispersing compound of Formula (II). Preferably, lubricating oilcompositions of the present invention will contain from about 0.005 to15 mass %, preferably from about 0.1 to about 5 mass %, more preferablyfrom about 0.5 to about 2 mass % of a compound of Formula (II).

Oils of lubricating viscosity useful in the context of the presentinvention may be selected from natural lubricating oils, syntheticlubricating oils and mixtures thereof. The lubricating oil may range inviscosity from light distillate mineral oils to heavy lubricating oilssuch as gasoline engine oils, mineral lubricating oils and heavy dutydiesel oils. Generally, the viscosity of the oil ranges from about 2centistokes to about 40 centistokes, especially from about 4 centistokesto about 20 centistokes, as measured at 100° C.

Natural oils include animal oils and vegetable oils (e.g., castor oil,lard oil); liquid petroleum oils and hydrorefined, solvent-treated oracid-treated mineral oils of the paraffinic, naphthenic and mixedparaffinic-naphthenic types. Oils of lubricating viscosity derived fromcoal or shale also serve as useful base oils.

Synthetic lubricating oils include hydrocarbon oils and halo-substitutedhydrocarbon oils such as polymerized and interpolymerized olefins (e.g.,polybutylenes, polypropylenes, propylene-isobutylene copolymers,chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes),poly(1-decenes)); alkylbenzenes (e.g., dodecylbenzenes,tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes);polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls); andalkylated diphenyl ethers and alkylated diphenyl sulfides andderivative, analogs and homologs thereof. Also useful are synthetic oilsderived from a gas to liquid process from Fischer-Tropsch synthesizedhydrocarbons, which are commonly referred to as gas to liquid, or “GTL”base oils.

Alkylene oxide polymers and interpolymers and derivatives thereof wherethe terminal hydroxyl groups have been modified by esterification,etherification, etc., constitute another class of known syntheticlubricating oils. These are exemplified by polyoxyalkylene polymersprepared by polymerization of ethylene oxide or propylene oxide, and thealkyl and aryl ethers of polyoxyalkylene polymers (e.g.,methyl-polyiso-propylene glycol ether having a molecular weight of 1000or diphenyl ether of poly-ethylene glycol having a molecular weight of1000 to 1500); and mono- and polycarboxylic esters thereof, for example,the acetic acid esters, mixed C₃-C₈ fatty acid esters and C₁₃ oxo aciddiester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils comprises theesters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkylsuccinic acids and alkenyl succinic acids, maleic acid, azelaic acid,suberic acid, sebasic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkylmalonic acids, alkenyl malonic acids) with avariety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycolmonoether, propylene glycol). Specific examples of such esters includesdibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctylsebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate,didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester oflinoleic acid dimer, and the complex ester formed by reacting one moleof sebacic acid with two moles of tetraethylene glycol and two moles of2-ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C₅ to C₁₂monocarboxylic acids and polyols and polyol esters such as neopentylglycol, trimethylolpropane, pentaerythritol, dipentaerythritol andtripentaerythritol.

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- orpolyaryloxysilicone oils and silicate oils comprise another useful classof synthetic lubricants; such oils include tetraethyl silicate,tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate,tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl)silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane, poly(methyl)siloxanesand poly(methylphenyl)siloxanes. Other synthetic lubricating oilsinclude liquid esters of phosphorous-containing acids (e.g., tricresylphosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid)and polymeric tetrahydrofurans.

The oil of lubricating viscosity may comprise a Group I, Group II orGroup III, base stock or base oil blends of the aforementioned basestocks. Preferably, the oil of lubricating viscosity is a Group II orGroup III base stock, or a mixture thereof, or a mixture of a Group Ibase stock and one or more a Group II and Group III. Preferably, a majoramount of the oil of lubricating viscosity is a Group II, Group III,Group IV or Group V base stock, or a mixture thereof. The base stock, orbase stock blend preferably has a saturate content of at least 65%, morepreferably at least 75%, such as at least 85%. Most preferably, the basestock, or base stock blend, has a saturate content of greater than 90%.Preferably, the oil or oil blend will have a sulfur content of less than1%, preferably less than 0.6%, most preferably less than 0.4%, byweight.

Preferably the volatility of the oil or oil blend, as measured by theNoack volatility test (ASTM D5880), is less than or equal to 30%,preferably less than or equal to 25%, more preferably less than or equalto 20%, most preferably less than or equal 16%. Preferably, theviscosity index (VI) of the oil or oil blend is at least 85, preferablyat least 100, most preferably from about 105 to 140.

Definitions for the base stocks and base oils in this invention are thesame as those found in the American Petroleum Institute (API)publication “Engine Oil Licensing and Certification System”, IndustryServices Department, Fourteenth Edition, December 1996, Addendum 1,December 1998. Said publication categorizes base stocks as follows:

-   -   a) Group I base stocks contain less than 90 percent saturates        and/or greater than 0.03 percent sulfur and have a viscosity        index greater than or equal to 80 and less than 120 using the        test methods specified in Table 1.    -   b) Group II base stocks contain greater than or equal to 90        percent saturates and less than or equal to 0.03 percent sulfur        and have a viscosity index greater than or equal to 80 and less        than 120 using the test methods specified in Table 1.    -   c) Group III base stocks contain greater than or equal to 90        percent saturates and less than or equal to 0.03 percent sulfur        and have a viscosity index greater than or equal to 120 using        the test methods specified in Table 1.    -   d) Group IV base stocks are polyalphaolefins (PAO).    -   e) Group V base stocks include all other base stocks not        included in Group I, II, III, or IV.

TABLE I Analytical Methods for Base Stock Property Test Method SaturatesASTM D 2007 Viscosity Index ASTM D 2270 Sulfur ASTM D 2622 ASTM D 4294ASTM D 4927 ASTM D 3120

Lubricating oil compositions of the present invention may furthercontain one or more ashless dispersants, which effectively reduceformation of deposits upon use in gasoline and diesel engines, whenadded to lubricating oils. Ashless dispersants useful in thecompositions of the present invention comprises an oil soluble polymericlong chain backbone having functional groups capable of associating withparticles to be dispersed. Typically, such dispersants comprise amine,alcohol, amide or ester polar moieties attached to the polymer backbone,often via a bridging group. The ashless dispersant may be, for example,selected from oil soluble salts, esters, amino-esters, amides, imidesand oxazolines of long chain hydrocarbon-substituted mono- andpolycarboxylic acids or anhydrides thereof; thiocarboxylate derivativesof long chain hydrocarbons; long chain aliphatic hydrocarbons havingpolyamine moieties attached directly thereto; and Mannich condensationproducts formed by condensing a long chain substituted phenol withformaldehyde and polyalkylene polyamine.

Preferably, the ashless dispersant is a “high molecular weight”dispersant having a number average molecular weight ( Mn) greater thanor equal to 4,000, such as between 4,000 and 20,000. The precisemolecular weight ranges will depend on the type of polymer used to formthe dispersant, the number of functional groups present, and the type ofpolar functional group employed. For example, for a polyisobutylenederivatized dispersant, a high molecular weight dispersant is one formedwith a polymer backbone having a number average molecular weight of fromabout 1680 to about 5600. Typical commercially availablepolyisobutylene-based dispersants contain polyisobutylene polymershaving a number average molecular weight ranging from about 900 to about2300, functionalized by maleic anhydride (MW=98), and derivatized withpolyamines having a molecular weight of from about 100 to about 350.Polymers of lower molecular weight may also be used to form highmolecular weight dispersants by incorporating multiple polymer chainsinto the dispersant, which can be accomplished using methods that areknow in the art.

Polymer molecular weight, specifically Mn, can be determined by variousknown techniques. One convenient method is gel permeation chromatography(GPC), which additionally provides molecular weight distributioninformation (see W. W. Yau, J. J. Kirkland and D. D. Bly, “Modern SizeExclusion Liquid Chromatography”, John Wiley and Sons, New York, 1979).If the molecular weight of an amine-containing dispersant (e.g.,PIBSA-polyamine or PIBSA-PAM) is being determined, the presence of theamine may cause the dispersant to be adsorbed by the column, leading toan inaccurate molecular weight determination. Persons familiar with theoperation of GPC equipment understand that this problem may beeliminated by using a mixed solvent system, such as tetrahydrofuran(THF) mixed with a minor amount of pyridine, as opposed to pure THF. Theproblem may also be addressed by capping the amine with acetic anhydrideand correcting the molecular weight based on the number of cappinggroups. Another useful method for determining molecular weight,particularly for lower molecular weight polymers, is vapor pressureosmometry (see, e.g., ASTM D3592).

The degree of polymerization D_(p) of a polymer is:

$D_{p} = {\sum\limits_{i}\frac{{Mn} \times {{mol}.\mspace{14mu} \%}\mspace{14mu} {monomer}\mspace{14mu} i}{100 \times {{mol}.\; {wt}}\mspace{11mu} {monomer}\mspace{14mu} i}}$

and thus for the copolymers of two monomers D_(p) may be calculated asfollows:

$D_{p} = \begin{matrix}\frac{{Mn} \times {{mol}.\mspace{14mu} \%}\mspace{14mu} {monomer}\mspace{14mu} 1}{100 \times {{mol}.\; {wt}}\mspace{11mu} {monomer}\mspace{14mu} 1} & \frac{{\,^{+}{Mn}} \times {{mol}.\mspace{14mu} \%}\mspace{14mu} {monomer}\mspace{14mu} 2}{100 \times {{mol}.\; {wt}}\mspace{11mu} {monomer}\mspace{14mu} 2}\end{matrix}$

Preferably, the degree of polymerization for the polymer backbones usedin the invention is at least 30, typically from 30 to 165, morepreferably 35 to 100.

The preferred hydrocarbons or polymers employed in this inventioninclude homopolymers, interpolymers or lower molecular weighthydrocarbons. One family of useful polymers comprise polymers ofethylene and/or at least one C₃ to C₂₈ alpha-olefin having the formulaH₂C═CHR¹, wherein R¹ is straight or branched chain alkyl radicalcomprising 1 to 26 carbon atoms and wherein the polymer containscarbon-to-carbon unsaturation, preferably a high degree of terminalethenylidene unsaturation. One preferred class of such polymers employedin this invention comprise interpolymers of ethylene and at least onealpha-olefin of the above formula, wherein R¹ is alkyl of from 1 to 18carbon atoms, and more preferably is alkyl of from 1 to 8 carbon atoms,and more preferably still of from 1 to 2 carbon atoms. Therefore, usefulalpha-olefin monomers and comonomers include, for example, propylene,butene-1, hexene-1, octene-1,4-methylpentene-1, decene-1, dodecene-1,tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1,octadecene-1, nonadecene-1, and mixtures thereof (e.g., mixtures ofpropylene and butene-1, and the like). Exemplary of such polymers arepropylene homopolymers, butene-1 homopolymers, propylene-butenecopolymers, ethylene-propylene copolymers, ethylene-butene-1 copolymersand the like, wherein the polymer contains at least some terminal and/orinternal unsaturation. Preferred polymers are unsaturated copolymers ofethylene and propylene and ethylene and butene-1. The interpolymers ofthis invention may contain a minor amount, e.g. 0.5 to 5 mole % of a C₄to C₁₈ non-conjugated diolefin comonomer. However, it is preferred thatthe polymers of this invention comprise only alpha-olefin homopolymers,interpolymers of alpha-olefin comonomers and interpolymers of ethyleneand alpha-olefin comonomers. The molar ethylene content of the polymersemployed in this invention is preferably in the range of 20 to 80%, andmore preferably 30 to 70%. When propylene and/or butene-1 are employedas comonomer(s) with ethylene, the ethylene content of such copolymersis most preferably between 45 and 65%, although higher or lower ethylenecontents may be present.

These polymers may be prepared by polymerizing alpha-olefin monomer, ormixtures of alpha-olefin monomers, or mixtures comprising ethylene andat least one C₃ to C₂₈ alpha-olefin monomer, in the presence of acatalyst system comprising at least one metallocene (e.g., acyclopentadienyl-transition metal compound) and an alumoxane compound.Using this process, a polymer in which 95% or more of the polymer chainspossess terminal ethenylidene-type unsaturation can be provided. Thepercentage of polymer chains exhibiting terminal ethenylideneunsaturation may be determined by FTIR spectroscopic analysis,titration, or C¹³ NMR. Interpolymers of this latter type may becharacterized by the formula POLY-C(R¹)═CH₂ wherein R¹ is C₁ to C₂₆alkyl, preferably C₁ to C₁₈ alkyl, more preferably C₁ to C₈ alkyl, andmost preferably C₁ to C₂ alkyl, (e.g., methyl or ethyl) and wherein POLYrepresents the polymer chain. The chain length of the R¹ alkyl groupwill vary depending on the comonomer(s) selected for use in thepolymerization. A minor amount of the polymer chains can containterminal ethenyl, i.e., vinyl, unsaturation, i.e. POLY-CH═CH₂, and aportion of the polymers can contain internal monounsaturation, e.g.POLY-CH═CH(R¹), wherein R¹ is as defined above. These terminallyunsaturated interpolymers may be prepared by known metallocene chemistryand may also be prepared as described in U.S. Pat. Nos. 5,498,809;5,663,130; 5,705,577; 5,814,715; 6,022,929 and 6,030,930.

Another useful class of polymers is polymers prepared by cationicpolymerization of isobutene, styrene, and the like. Common polymers fromthis class include polyisobutenes obtained by polymerization of a C₄refinery stream having a butene content of about 35 to about 75% by wt.,and an isobutene content of about 30 to about 60% by wt., in thepresence of a Lewis acid catalyst, such as aluminum trichloride or borontrifluoride. A preferred source of monomer for making poly-n-butenes ispetroleum feed streams such as Raffinate II. These feedstocks are isdisclosed in the art such as in U.S. Pat. No. 4,952,739. Polyisobutyleneis a most preferred backbone of the present invention because it isreadily available by cationic polymerization from butene streams (e.g.,using AlCl₃ or BF₃ catalysts). Such polyisobutylenes generally containresidual unsaturation in amounts of about one ethylenic double bond perpolymer chain, positioned along the chain.

As noted above, the polyisobutylene polymers employed are generallybased on a hydrocarbon chain of from about 900 to 2,300. Methods formaking polyisobutylene are known. Polyisobutylene can be functionalizedby halogenation (e.g. chlorination), the thermal “ene” reaction, or byfree radical grafting using a catalyst (e.g. peroxide), as describedbelow.

Processes for reacting polymeric hydrocarbons with unsaturatedcarboxylic acids, anhydrides or esters and the preparation ofderivatives from such compounds are disclosed in U.S. Pat. Nos.3,087,936; 3,172,892; 3,215,707; 3,231,587; 3,272,746; 3,275,554;3,381,022; 3,442,808; 3,565,804; 3,912,764; 4,110,349; 4,234,435; andGB-A-1,440,219. The polymer or hydrocarbon may be functionalized, forexample, with carboxylic acid producing moieties (preferably acid oranhydride) by reacting the polymer or hydrocarbon under conditions thatresult in the addition of functional moieties or agents, i.e., acid,anhydride, ester moieties, etc., onto the polymer or hydrocarbon chainsprimarily at sites of carbon-to-carbon unsaturation (also referred to asethylenic or olefinic unsaturation) using the halogen assistedfunctionalization (e.g. chlorination) process or the thermal “ene”reaction.

When using the free radical grafting process employing a catalyst (e.g.peroxide), the functionalization is randomly effected along the polymerchain. Selective functionalization can be accomplished by halogenating,e.g., chlorinating or brominating the unsaturated α-olefin polymer toabout 1 to 8 wt. %, preferably 3 to 7 wt. % chlorine, or bromine, basedon the weight of polymer or hydrocarbon, by passing the chlorine orbromine through the polymer at a temperature of 60 to 250° C.,preferably 110 to 160° C., e.g., 120 to 140° C., for about 0.5 to 10,preferably 1 to 7 hours. The halogenated polymer or hydrocarbon(hereinafter backbones) can then be reacted with sufficientmonounsaturated reactant capable of adding functional moieties to thebackbone, e.g., monounsaturated carboxylic reactant, at 100 to 250° C.,usually about 180° C. to 235° C., for about 0.5 to 10, e.g., 3 to 8hours, such that the product obtained will contain the desired number ofmoles of the monounsaturated carboxylic reactant per mole of thehalogenated backbones. Alternatively, the backbone and themonounsaturated carboxylic reactant can be mixed and heated while addingchlorine to the hot material.

The hydrocarbon or polymer backbone can be functionalized, e.g., withcarboxylic acid producing moieties (preferably acid or anhydridemoieties) selectively at sites of carbon-to-carbon unsaturation on thepolymer or hydrocarbon chains, or randomly along chains using the threeprocesses mentioned above, or combinations thereof, in any sequence.

The preferred monounsaturated reactants that are used to functionalizethe backbone comprise mono- and dicarboxylic acid material, i.e., acid,anhydride, or acid ester material, including (i) monounsaturated C₄ toC₁₀ dicarboxylic acid wherein (a) the carboxyl groups are vicinyl,(i.e., located on adjacent carbon atoms) and (b) at least one,preferably both, of said adjacent carbon atoms are part of said monounsaturation; (ii) derivatives of (i) such as anhydrides or C_(I) to C₅alcohol derived mono- or diesters of (i); (iii) monounsaturated C₃ toC₁₀ monocarboxylic acid wherein the carbon-carbon double bond isconjugated with the carboxy group, i.e., of the structure —C═C—CO—; and(iv) derivatives of (iii) such as C₁ to C₅ alcohol derived mono- ordiesters of (iii). Mixtures of monounsaturated carboxylic materials(i)-(iv) also may be used. Upon reaction with the backbone, themonounsaturation of the monounsaturated carboxylic reactant becomessaturated. Thus, for example, maleic anhydride becomesbackbone-substituted succinic anhydride, and acrylic acid becomesbackbone-substituted propionic acid. Exemplary of such monounsaturatedcarboxylic reactants are fumaric acid, itaconic acid, maleic acid,maleic anhydride, chloromaleic acid, chloromaleic anhydride, acrylicacid, methacrylic acid, crotonic acid, cinnamic acid, and lower alkyl(e.g., C₁ to C₄ alkyl) acid esters of the foregoing, e.g., methylmaleate, ethyl fumarate, and methyl fumarate. The monounsaturatedcarboxylic reactant, preferably maleic anhydride, typically will be usedin an amount ranging from about 0.01 to about 20 wt. %. preferably 0.5to 10 wt. %, based on the weight of the polymer or hydrocarbon.

While chlorination normally helps increase the reactivity of startingolefin polymers with monounsaturated functionalizing reactant, it is notnecessary with the polymers or hydrocarbons contemplated for use in thepresent invention, particularly those preferred polymers or hydrocarbonswhich possess a high terminal bond content and reactivity. Preferably,therefore, the backbone and the monounsaturated functionality reactant,e.g., carboxylic reactant, are contacted at elevated temperature tocause an initial thermal “ene” reaction to take place. Ene reactions areknown.

The hydrocarbon or polymer backbone can be functionalized by randomattachment of functional moieties along the polymer chains by a varietyof methods. For example, the polymer, in solution or in solid form, maybe grafted with the monounsaturated carboxylic reactant, as describedabove, in the presence of a free-radical initiator. When performed insolution, the grafting takes place at an elevated temperature in therange of about 100 to 260° C., preferably 120 to 240° C. Preferably,free-radical initiated grafting is accomplished in a mineral lubricatingoil solution containing, for example, 1 to 50 wt. %, preferably 5 to 30wt. % polymer based on the initial total oil solution.

The free-radical initiators that may be used are peroxides,hydroperoxides, and azo compounds, preferably those that have a boilingpoint greater than about 100° C. and decompose thermally within thegrafting temperature range to provide free-radicals. Representative ofthese free-radical initiators are azobutyronitrile, bis-tertiary-butylperoxide and dicumene peroxide. The initiator, when used, typically isused in an amount of between 0.005% and 1% by weight based on the weightof the reaction mixture solution. Typically, the aforesaidmonounsaturated carboxylic reactant material and free-radical initiatorare used in a weight ratio range of from about 1.0:1 to 30:1, preferably3:1 to 6:1. The grafting is preferably carried out in an inertatmosphere, such as under nitrogen blanketing. The resulting graftedpolymer is characterized by having carboxylic acid (or ester oranhydride) moieties randomly attached along the polymer chains: it beingunderstood, of course, that some of the polymer chains remain ungrafted.The free radical grafting described above can be used for the otherpolymers and hydrocarbons of the present invention.

The functionalized oil-soluble polymeric hydrocarbon backbone may thenbe further derivatized with a nucleophilic reactant, such as an amine,amino-alcohol, to alcohol, metal compound, or mixture thereof, to form acorresponding derivative. Useful amine compounds for derivatizingfunctionalized polymers comprise at least one amine and can comprise oneor more additional amine or other reactive or polar groups. These aminesmay be hydrocarbyl amines or may be predominantly hydrocarbyl amines inwhich the hydrocarbyl group includes other groups, e.g., hydroxy groups,alkoxy groups, amide groups, nitriles, imidazoline groups, and the like.Particularly useful amine compounds include mono- and polyamines, e.g.,polyalkene and polyoxyalkylene polyamines of about 2 to 60, such as 2 to40 (e.g., 3 to 20) total carbon atoms having about 1 to 12, such as 3 to12, and preferably 3 to 9 nitrogen atoms per molecule. Mixtures of aminecompounds may advantageously be used, such as those prepared by reactionof alkylene dihalide with ammonia.

Preferred amines are aliphatic saturated amines, including, for example,1,2-diaminoethane; 1,3-diaminopropane; 1,4-diaminobutane;1,6-diaminohexane; polyethylene amines such as diethylene triamine;triethylene tetramine; tetraethylene pentamine; and polypropyleneaminessuch as 1,2-propylene diamine; and di-(1,2-propylene)triamine.

Other useful amine compounds include: alicyclic diamines such as1,4-di(aminomethyl)cyclohexane and heterocyclic nitrogen compounds suchas imidazolines. Another useful class of amines is the polyamido andrelated amido-amines as disclosed in U.S. Pat. Nos. 4,857,217;4,956,107; 4,963,275; and 5,229,022. Also usable istris(hydroxymethyl)amino methane (TAM) as described in U.S. Pat. Nos.4,102,798; 4,113,639; 4,116,876; and UK 989,409. Dendrimers, star-likeamines, and comb-structured amines may also be used. Similarly, one mayuse condensed amines, as described in U.S. Pat. No. 5,053,152. Thefunctionalized polymer is reacted with the amine compound usingconventional techniques as described, for example, in U.S. Pat. Nos.4,234,435 and 5,229,022, as well as in EP-A-208,560.

The functionalized, oil-soluble polymeric hydrocarbon backbones may alsobe derivatized with hydroxy compounds such as monohydric and polyhydricalcohols, or with aromatic compounds such as phenols and naphthols.Preferred polyhydric alcohols include alkylene glycols in which thealkylene radical contains from 2 to 8 carbon atoms. Other usefulpolyhydric alcohols include glycerol, mono-oleate of glycerol,monostearate of glycerol, monomethyl ether of glycerol, pentaerythritol,dipentaerythritol, and mixtures thereof. An ester dispersant may also bederived from unsaturated alcohols, such as allyl alcohol, cinnamylalcohol, propargyl alcohol, 1-cyclohexene-3-ol, and (oleyl alcohol.Still other classes of alcohols capable of yielding ashless dispersantscomprise ether-alcohols, including oxy-alkylene and oxy-arylene. Suchether-alcohols are exemplified by ether-alcohols having up to 150oxy-alkylene radicals in which the alkylene radical contains from 1 to 8carbon atoms. The ester dispersants may be di-esters of succinic acidsor acid-esters, i.e., partially esterified succinic acids, as well aspartially esterified polyhydric alcohols or phenols, i.e., esters havingfree alcohols or phenolic hydroxy radicals. An ester dispersant may beprepared by any one of several known methods as described, for example,in U.S. Pat. No. 3,381,022.

Preferred groups of dispersant include polyamine-derivatized polyα-olefin, dispersants, particularly ethylene/butene alpha-olefin andpolyisobutylene-based dispersants. Particularly preferred are ashlessdispersants derived from polyisobutylene substituted with succinicanhydride groups and reacted with polyethylene amines, e.g.,polyethylene diamine, tetraethylene pentamine; or a polyoxyalkylenepolyamine, e.g., polyoxypropylene diamine, trimethylolaminomethane; ahydroxy compound, e.g., pentaerythritol; and combinations thereof. Oneparticularly preferred dispersant combination is a combination of (A)polyisobutylene substituted with succinic anhydride groups and reactedwith (B) a hydroxy compound, e.g., pentaerythritol; (C) apolyoxyalkylene polyamine, e.g., polyoxypropylene diamine, or (D) apolyalkylene diamine, e.g., polyethylene diamine and tetraethylenepentamine using about 0.3 to about 2 moles of (B), (C) and/or (D) permole of (A). Another preferred dispersant combination comprises acombination of (A) polyisobutenyl succinic anhydride with (B) apolyalkylene polyamine, e.g., tetraethylene pentamine, and (C) apolyhydric alcohol or polyhydroxy-substituted aliphatic primary amine,e.g., pentaerythritol or trismethylolaminomethane, as described in U.S.Pat. No. 3,632,511.

Another class of ashless dispersants comprises Mannich base condensationproducts. Generally, these products are prepared by condensing about onemole of an alkyl-substituted mono- or polyhydroxy benzene with about 1to 2.5 moles of carbonyl compound(s) (e.g., formaldehyde andparaformaldehyde) and about 0.5 to 2 moles of polyalkylene polyamine, asdisclosed, for example, in U.S. Pat. No. 3,442,808. Such Mannich basecondensation products may include a polymer product of a metallocenecatalyzed polymerization as a substituent on the benzene group, or maybe reacted with a compound containing such a polymer substituted on asuccinic anhydride in a manner similar to that described in U.S. Pat.No. 3,442,808. Examples of functionalized and/or derivatized olefinpolymers synthesized using metallocene catalyst systems are described inthe publications identified supra.

The dispersant can be further post treated by a variety of conventionalpost treatments such as boration, as generally taught in U.S. Pat. Nos.3,087,936 and 3,254,025. Boration of the dispersant is readilyaccomplished by treating an acyl nitrogen-containing dispersant with aboron compound such as boron oxide, boron halide boron acids, and estersof boron acids, in an amount sufficient to provide from about 0.1 toabout 20 atomic proportions of boron for each mole of acylated nitrogencomposition. Useful dispersants contain from about 0.05 to about 2.0mass %, e.g., from about 0.05 to about 0.7 mass % boron. The boron,which appears in the product as dehydrated boric acid polymers(primarily (HBO₂)₃), is believed to attach to the dispersant imides anddiimides as amine salts, e.g., the metaborate salt of the diimide.Boration can be carried out by adding from about 0.5 to 4 mass %, e.g.,from about 1 to about 3 mass % (based on the mass of acyl nitrogencompound) of a boron compound, preferably boric acid, usually as aslurry, to the acyl nitrogen compound and heating with stirring at fromabout 135° C. to about 190° C., e.g., 140° C. to 170° C., for from about1 to about 5 hours, followed by nitrogen stripping. Alternatively, theboron treatment can be conducted by adding boric acid to a hot reactionmixture of the dicarboxylic acid material and amine, while removingwater. Other post reaction processes commonly known in the art can alsobe applied.

The dispersant may also be further post treated by reaction with aso-called “capping agent”. Conventionally, nitrogen-containingdispersants have been “capped” to reduce the adverse effect suchdispersants have on the fluoroelastomer engine seals. Numerous cappingagents and methods are known. Of the known “capping agents”, those thatconvert basic dispersant amino groups to non-basic moieties (e.g., amidoor imido groups) are most suitable. The reaction of anitrogen-containing dispersant and alkyl acetoacetate (e.g., ethylacetoacetate (EAA)) is described, for example, in U.S. Pat. Nos.4,839,071; 4,839,072 and 4,579,675. The reaction of anitrogen-containing dispersant and formic acid is described, forexample, in U.S. Pat. No. 3,185,704. The reaction product of anitrogen-containing dispersant and other suitable capping agents aredescribed in U.S. Pat. Nos. 4,663,064 (glycolic acid); 4,612,132;5,334,321; 5,356,552; 5,716,912; 5,849,676; 5,861,363 (alkyl andalkylene carbonates, e.g., ethylene carbonate); 5,328,622(mono-epoxide); 5,026,495; 5,085,788; 5,259,906; 5,407,591 (poly (e.g.,bis)-epoxides) and 4,686,054 (maleic anhydride or succinic anhydride).The foregoing list is not exhaustive and other methods of cappingnitrogen-containing dispersants are known to those skilled in the art.

For adequate piston deposit control, a nitrogen-containing dispersantcan be added in an amount providing the lubricating oil composition withfrom about 0.03 mass % to about 0.15 mass %, preferably from about 0.07to about 0.12 mass %, of nitrogen.

Additional additives may be incorporated in the compositions of theinvention to enable them to meet particular requirements. Examples ofadditives which may be included in the lubricating oil compositions aredetergents, metal rust inhibitors, viscosity index improvers, corrosioninhibitors, oxidation inhibitors, friction modifiers, other dispersants,anti-foaming agents, anti-wear agents and pour point depressants. Someare discussed in further detail below.

Metal-containing or ash-forming detergents function both as detergentsto reduce or remove deposits and as acid neutralizers or rustinhibitors, thereby reducing wear and corrosion and extending enginelife. Detergents generally comprise a polar head with a long hydrophobictail, with the polar head comprising a metal salt of an acidic organiccompound. The salts may contain a substantially stoichiometric amount ofthe metal in which case they are usually described as normal or neutralsalts, and would typically have a total base number or TBN (as can bemeasured by ASTM D2896) of from 0 to 80. A large amount of a metal basemay be incorporated by reacting excess metal compound (e.g., an oxide orhydroxide) with an acidic gas (e.g., carbon dioxide). The resultingoverbased detergent comprises neutralized detergent as the outer layerof a metal base (e.g. carbonate) micelle. Such overbased detergents mayhave a TBN of 150 or greater, and typically will have a TBN of from 250to 450 or more.

Detergents that may be used include oil-soluble neutral and overbasedsulfonates, phenates, sulfurized phenates, thiophosphonates,salicylates, and naphthenates and other oil-soluble carboxylates of ametal, particularly the alkali or alkaline earth metals, e.g., sodium,potassium, lithium, calcium, and magnesium. The most commonly usedmetals are calcium and magnesium, which may both be present indetergents used in a lubricant, and mixtures of calcium and/or magnesiumwith sodium. Particularly convenient metal detergents are neutral andoverbased calcium sulfonates having TBN of from 20 to 450 TBN, andneutral and overbased calcium phenates and sulfurized phenates havingTBN of from 50 to 450. Combinations of detergents, whether overbased orneutral or both, may be used.

Sulfonates may be prepared from sulfonic acids which are typicallyobtained by the sulfonation of alkyl substituted aromatic hydrocarbonssuch as those obtained from the fractionation of petroleum or by thealkylation of aromatic hydrocarbons. Examples included those obtained byalkylating benzene, toluene, xylene, naphthalene, diphenyl or theirhalogen derivatives such as chlorobenzene, chlorotoluene andchloronaphthalene. The alkylation may be carried out in the presence ofa catalyst with alkylating agents having from about 3 to more than 70carbon atoms. The alkaryl sulfonates usually contain from about 9 toabout 80 or more carbon atoms, preferably from about 16 to about 60carbon atoms per alkyl substituted aromatic moiety.

The oil soluble sulfonates or alkaryl sulfonic acids may be neutralizedwith oxides, hydroxides, alkoxides, carbonates, carboxylate, sulfides,hydrosulfides, nitrates, borates and ethers of the metal. The amount ofmetal compound is chosen having regard to the desired TBN of the finalproduct but typically ranges from about 100 to 220 mass % (preferably atleast 125 mass %) of that stoichiometrically required.

Metal salts of phenols and sulfurized phenols are prepared by reactionwith an appropriate metal compound such as an oxide or hydroxide andneutral or overbased products may be obtained by methods well known inthe art. Sulfurized phenols may be prepared by reacting a phenol withsulfur or a sulfur containing compound such as hydrogen sulfide, sulfurmonohalide or sulfur dihalide, to form products which are generallymixtures of compounds in which 2 or more phenols are bridged by sulfurcontaining bridges.

Dihydrocarbyl dithiophosphate metal salts are frequently used asantiwear and antioxidant agents. The metal may be an alkali or alkalineearth metal, or aluminum, lead, tin, molybdenum, manganese, nickel orcopper. The zinc salts are most commonly used in lubricating oil inamounts of 0.1 to 10, preferably 0.2 to 2 wt. %, based upon the totalweight of the lubricating oil composition. They may be prepared inaccordance with known techniques by first forming a dihydrocarbyldithiophosphoric acid (DDPA), usually by reaction of one or more alcoholor a phenol with P₂S₅ and then neutralizing the formed DDPA with a zinccompound. For example, a dithiophosphoric acid may be made by reactingmixtures of primary and secondary alcohols. Alternatively, multipledithiophosphoric acids can be prepared where the hydrocarbyl groups onone are entirely secondary in character and the hydrocarbyl groups onthe others are entirely primary in character. To make the zinc salt, anybasic or neutral zinc compound could be used but the oxides, hydroxidesand carbonates are most generally employed. Commercial additivesfrequently contain an excess of zinc due to the use of an excess of thebasic zinc compound in the neutralization reaction.

The preferred zinc dihydrocarbyl dithiophosphates are oil soluble saltsof dihydrocarbyl dithiophosphoric acids and may be represented by thefollowing formula:

wherein R and R′ may be the same or different hydrocarbyl radicalscontaining from 1 to 18, preferably 2 to 12, carbon atoms and includingradicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl andcycloaliphatic radicals. Particularly preferred as R and R′groups arealkyl groups of 2 to 8 carbon atoms. Thus, the radicals may, forexample, be ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl,amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl, octadecyl,2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl,propenyl, butenyl. In order to obtain oil solubility, the total numberof carbon atoms (i.e. R and R′) in the dithiophosphoric acid willgenerally be about 5 or greater. The zinc dihydrocarbyl dithiophosphatecan therefore comprise zinc dialkyl dithiophosphates. The presentinvention may be particularly useful when used with lubricantcompositions containing phosphorus levels of from about 0.02 to about0.12 mass %, such as from about 0.03 to about 0.10 mass %, or from about0.05 to about 0.08 mass %, based on the total mass of the composition.In one preferred embodiment, lubricating oil compositions of the presentinvention contain zinc dialkyl dithiophosphate derived predominantly(e.g., over 50 mol. %, such as over 60 mol. %) from secondary alcohols.

Oxidation inhibitors or antioxidants reduce the tendency of mineral oilsto deteriorate in service. Oxidative deterioration can be evidenced bysludge in the lubricant, varnish-like deposits on the metal surfaces,and by viscosity growth. Such oxidation inhibitors include hinderedphenols, alkaline earth metal salts of alkylphenolthioesters havingpreferably C₅ to C₁₂ alkyl side chains, calcium nonylphenol sulfide, oilsoluble phenates and sulfurized phenates, phosphosulfurized orsulfurized hydrocarbons, phosphorous esters, metal thiocarbamates, oilsoluble copper compounds as described in U.S. Pat. No. 4,867,890, andmolybdenum-containing compounds.

Typical oil soluble aromatic amines having at least two aromatic groupsattached directly to one amine nitrogen contain from 6 to 16 carbonatoms. The amines may contain more than two aromatic groups. Compoundshaving a total of at least three aromatic groups in which two aromaticgroups are linked by a covalent bond or by an atom or group (e.g., anoxygen or sulfur atom, or a —CO—, —SO₂— or alkylene group) and two aredirectly attached to one amine nitrogen also considered aromatic amineshaving at least two aromatic groups attached directly to the nitrogen.The aromatic rings are typically substituted by one or more substituentsselected from alkyl, cycloalkyl, alkoxy, aryloxy, acyl, acylamino,hydroxy, and nitro groups.

Multiple antioxidants are commonly employed in combination. In onepreferred embodiment, lubricating oil compositions of the presentinvention contain from about 0.1 to about 1.2 mass % of aminicantioxidant and from about 0.1 to about 3 mass % of phenolicantioxidant. In another preferred embodiment, lubricating oilcompositions of the present invention contain from about 0.1 to about1.2 mass % of aminic antioxidant, from about 0.1 to about 3 mass % ofphenolic antioxidant and a molybdenum compound in an amount providingthe lubricating oil composition from about 10 to about 1000 ppm ofmolybdenum.

Representative examples of suitable viscosity modifiers arepolyisobutylene, copolymers of ethylene and propylene,polymethacrylates, methacrylate copolymers, copolymers of an unsaturateddicarboxylic acid and a vinyl compound, interpolymers of styrene andacrylic esters, and partially hydrogenated copolymers ofstyrene/isoprene, styrene/butadiene, and isoprene/butadiene, as well asthe partially hydrogenated homopolymers of butadiene and isoprene.

Friction modifiers and fuel economy agents that are compatible with theother ingredients of the final oil may also be included. Examples ofsuch materials include glyceryl monoesters of higher fatty acids, forexample, glyceryl mono-oleate; esters of long chain polycarboxylic acidswith diols, for example, the butane diol ester of a dimerizedunsaturated fatty acid; oxazoline compounds; and alkoxylatedalkyl-substituted mono-amines, diamines and alkyl ether amines, forexample, ethoxylated tallow amine and ethoxylated tallow ether amine.

Other known friction modifiers comprise oil-soluble organo-molybdenumcompounds. Such organo-molybdenum friction modifiers also provideantioxidant and antiwear credits to a lubricating oil composition.Examples of such oil soluble organo-molybdenum compounds includedithiocarbamates, dithiophosphates, dithiophosphinates, xanthates,thioxanthates, sulfides, and the like, and mixtures thereof.Particularly preferred are molybdenum dithiocarbamates,dialkyldithiophosphates, alkyl xanthates and alkylthioxanthates.

Additionally, the molybdenum compound may be an acidic molybdenumcompound. These compounds will react with a basic nitrogen compound asmeasured by ASTM test D-664 or D-2896 titration procedure and aretypically hexavalent. Included are molybdic acid, ammonium molybdate,sodium molybdate, potassium molybdate, and other alkaline metalmolybdates and other molybdenum salts, e.g., hydrogen sodium molybdate,MoOCl₄, MoO₂Br₂, Mo₂O₃Cl₆, molybdenum trioxide or similar acidicmolybdenum compounds.

Among the molybdenum compounds useful in the compositions of thisinvention are organo-molybdenum compounds of the formula

Mo(ROCS₂)₄ and

Mo(RSCS₂)₄

wherein R is an organo group selected from the group consisting ofalkyl, aryl, aralkyl and alkoxyalkyl, generally of from 1 to 30 carbonatoms, and preferably 2 to 12 carbon atoms and most preferably alkyl of2 to 12 carbon atoms. Especially preferred are thedialkyldithiocarbamates of molybdenum.

Another group of organo-molybdenum compounds useful in the lubricatingcompositions of this invention are trinuclear molybdenum compounds,especially those of the formula Mo₃S_(k)L_(n)Q_(z) and mixtures thereofwherein the L are independently selected ligands having organo groupswith a sufficient number of carbon atoms to render the compound solubleor dispersible in the oil, n is from 1 to 4, k varies from 4 through 7,Q is selected from the group of neutral electron donating compounds suchas water, amines, alcohols, phosphines, and ethers, and z ranges from 0to 5 and includes non-stoichiometric values. At least 21 total carbonatoms should be present among all the ligand organo groups, such as atleast 25, at least 30, or at least 35 carbon atoms.

A dispersant—viscosity index improver functions as both a viscosityindex improver and as a dispersant. Examples of dispersant—viscosityindex improvers include reaction products of amines, for examplepolyamines, with a hydrocarbyl-substituted mono- or dicarboxylic acid inwhich the hydrocarbyl substituent comprises a chain of sufficient lengthto impart viscosity index improving properties to the compounds. Ingeneral, the viscosity index improver dispersant may be, for example, apolymer of a C₄ to C₂₄ unsaturated ester of vinyl alcohol or a C₃ to C₁₀unsaturated mono-carboxylic acid or a C₄ to C₁₀ di-carboxylic acid withan unsaturated nitrogen-containing monomer having 4 to 20 carbon atoms;a polymer of a C₂ to C₂₀ olefin with an unsaturated C₃ to C₁₀ mono- ordi-carboxylic acid neutralized with an amine, hydroxyl amine or analcohol; or a polymer of ethylene with a C₃ to C₂₀ olefin furtherreacted either by grafting a C₄ to C₂₀ unsaturated nitrogen-containingmonomer thereon or by grafting an unsaturated acid onto the polymerbackbone and then reacting carboxylic acid groups of the grafted acidwith an amine, hydroxy amine or alcohol.

Pour point depressants, otherwise known as lube oil flow improvers(LOFI), lower the minimum temperature at which the fluid will flow orcan be poured. Such additives are well known. Typical of those additivesthat improve the low temperature fluidity of the fluid are C₈ to C₁₈dialkyl fumarate/vinyl acetate copolymers, and polymethacrylates. Foamcontrol can be provided by an antifoamant of the polysiloxane type, forexample, silicone oil or polydimethyl siloxane.

Some of the above-mentioned additives can provide a multiplicity ofeffects; thus for example, a single additive may act as adispersant-oxidation inhibitor. This approach is well known and need notbe further elaborated herein.

In one preferred embodiment, lubricating oil compositions of the presentinvention further comprise, in combination with a compound of Formula(II), a high molecular weight polymer comprising (i) copolymers ofhydrogenated poly(monovinyl aromatic hydrocarbon) and poly (conjugateddiene), wherein the hydrogenated poly(monovinyl aromatic hydrocarbon)segment comprises at least about 20 wt. % of the copolymer; (ii) olefincopolymers containing alkyl or aryl amine, or amide groups,nitrogen-containing heterocyclic groups or ester linkages and/or (iii)acrylate or alkylacrylate copolymer derivatives having dispersinggroups.

Copolymers of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene), wherein the hydrogenated poly(monovinyl aromatichydrocarbon) segment comprises at least about 20 wt. % of the copolymer(hereinafter “Polymer (i)”) are known viscosity modifiers and arecommercially available as, for example, SV151 (Infineum USA L.P.).Preferred monovinyl aromatic hydrocarbon monomers useful in theformation of such materials include styrene, alkyl-substituted styrene,alkoxy-substituted styrene, vinyl naphthalene and alkyl-substitutedvinyl naphthalene. The alkyl and alkoxy substituents may typicallycomprise from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms.The number of alkyl or alkoxy substituents per molecule, if present, mayrange from 1 to 3, and is preferably one.

Preferred conjugated diene monomers useful in the formation of suchmaterials include those conjugated dienes containing from 4 to 24 carbonatoms, such as 1,3-butadiene, isoprene, piperylene, methylpentadiene,2-phenyl-1,3-butadiene, 3,4-dimethyl-1,3-hexadiene and4,5-diethyl-1,3-octadiene.

Preferred are block copolymers comprising at least one poly(monovinylaromatic hydrocarbon) block and at least one poly (conjugated diene)block. Preferred block copolymers are selected from those of the formulaAB, wherein A represents a block polymer of predominantly poly(monovinylaromatic hydrocarbon), B represents a block of predominantly poly(conjugated diene).

Preferably, the poly(conjugated diene) block is partially or fullyhydrogenated. More preferably, the monovinyl aromatic hydrocarbons arestyrene and/or alkyl-substituted styrene, particularly styrene.Preferred conjugated dienes are those containing from 4 to 12 carbonatoms, more preferably from 4 to 6 carbon atoms. Isoprene and butadieneare the most preferred conjugated diene monomers. Preferably, thepoly(isoprene) is hydrogenated.

Block copolymers and selectively hydrogenated block copolymers are knownin the art and are commercially available. Such block copolymers can bemade can be made by anionic polymerization with an alkali metalinitiator such as sec-butyllithium, as described, for example, in U.S.Pat. Nos. 4,764,572; 3,231,635; 3,700,633 and 5,194,530.

The poly(conjugated diene) block(s) of the block copolymer may beselectively hydrogenated, typically to a degree such that the residualethylenic unsaturation of the block is reduced to at most 20%, morepreferably at most 5%, most preferably at most 2% of the unsaturationlevel before hydrogenation. The hydrogenation of these copolymers may becarried out using a variety of well established processes includinghydrogenation in the presence of such catalysts as Raney Nickel, noblemetals such as platinum and the like, soluble transition metal catalystsand titanium catalysts as described in U.S. Pat. No. 5,299,464.

Sequential polymerization or reaction with divalent coupling agents canbe used to form linear polymers. It is also known that a coupling agentcan be formed in-situ by the polymerization of a monomer having twoseparately polymerizable vinyl groups such a divinylbenzene to providestar polymers having from about 6 to about 50 arms. Di- and multivalentcoupling agents containing 2 to 8 functional groups, and methods offorming star polymers are well known and such materials are availablecommercially.

The second class of high molecular weight polymers are olefin copolymers(OCP) containing dispersing groups such as alkyl or aryl amine, or amidegroups, nitrogen-containing heterocyclic groups or ester linkages(hereinafter “Polymer (ii)”). These polymers have been usedconventionally as multifunctional dispersant viscosity modifiers inlubricating oil compositions. The olefin copolymers can comprise anycombination of olefin monomers, but are most commonly ethylene and atleast one other α-olefin. The at least one other α-olefin monomer isconventionally an α-olefin having 3 to 18 carbon atoms, and is mostpreferably propylene. As is well known, copolymers of ethylene andhigher α-olefins, such as propylene, often include other polymerizablemonomers. Typical of these other monomers are non-conjugated dienes suchas the following, non-limiting examples

-   -   a. straight chain dienes such as 1,4-hexadiene and        1,6-octadiene;    -   b. branched chain acyclic dienes such as 5-methyl-1,4-hexadiene;        3,7-dimethyl-1,6-octadiene; 3,7-dimethyl-1,7-octadiene and mixed        isomers of dihydro-mycene and dihydroocinene;    -   c. single ring alicyclic dienes such as 1,4-cyclohexadiene;        1,5-cyclooctadiene; and 1,5-cyclododecadiene;    -   d. multi-ring alicyclic fused and bridged ring dienes such as        tetrahydroindene; methyltetrahydroindene; dicyclopentadiene;        bicyclo-(2,2,1)-hepta-2,5-diene; alkenyl, alkylidene,        cycloalkenyl and cycloalkylidene norbornenes such as        5-methylene-2-norbornene (MNB), 5-ethylidene-2-norbornene (ENB),        5-propylene-2-norbornene, 5-isoproylidene-2-norbornene,        5-(4-cyclopentyenyl)-2-norbornene;        5-cyclohexylidene-2-norbornene.

Of the non-conjugated dienes typically used, dienes containing at leastone of the double bonds in a strained ring are preferred. The mostpreferred diene is 5-ethylidene-2-norbornene (ENB). The amount of diene(wt. basis) in the copolymer can be from 0% to about 20%, with 0% toabout 15% being preferred, and 0% to about 10% being most preferred. Asalready noted, the most preferred olefin copolymer isethylene-propylene. The average ethylene content of the copolymer can beas low as 20% on a weight basis. The preferred minimum ethylene contentis about 25%. A more preferred minimum is 30%. The maximum ethylenecontent can be as high as 90% on a weight bas, preferably the maximumethylene content is 85%, most preferably about 80%. Preferably, theolefin copolymers contain from about 35 to 75 wt. % ethylene, morepreferably from about 50 to about 70 wt. % of ethylene.

The molecular weight (number average) of the olefin copolymer can be aslow as 2000, but the preferred minimum is 10,000. The more preferredminimum is 15,000, with the most preferred minimum number averagemolecular weight being 20,000. It is believed that the maximum numberaverage molecular weight can be as high as 12,000,000. The preferredmaximum is about 1,000,000, with the most preferred maximum being about750,000. An especially preferred range of number average molecularweight for the olefin copolymers of the present invention is from about50,000 to about 500,000.

Olefin copolymers can be rendered multifunctional by attaching anitroge-containing polar moiety (e.g., amine, amine-alcohol or amide) tothe polymer backbone. The nitrogen-containing moieties areconventionally of the formula R—N—R′R″, wherein R, R′ and R″ areindependently alkyl, aryl of H. Also suitable are aromatic amines of theformula R—R′—NH—R″—R, wherein R′ and R″ are aromatic groups and each areis alkyl. The most common method for forming a multifunctional OCPviscosity modifier involves the free radical addition of thenitrogen-containing polar moiety to the polymer backbone. Thenitrogen-containing polar moiety can be attached to the polymer using adouble bond within the polymer (i.e., the double bond of the dieneportion of an EPDM polymer, or by reacting the polymer with a compoundproviding a bridging group containing a double bond (e.g., maleicanhydride as described, for example, in U.S. Pat. Nos. 3,316,177;3,326,804; and carboxylic acids and ketones as described, for example,in U.S. Pat. No. 4,068,056), and subsequently derivatizing thefunctionalized polymer with the nitrogen-containing polar moiety. A morecomplete list of nitrogen-containing compounds that can be reacted withthe functionalized OCP are described infra, in the discussion ofdispersants. Multifunctionalized OCPs and methods for farming suchmaterials are known in the art and are available commercially (e.g.,HITEC 5777 available from Afton Corporation and PA 1160, a product ofDutch Staaten Minen).

Preferred are low ethylene olefin copolymers containing about 50 wt. %ethylene and having a number average molecular weight between 10,000 and20,000 grafted with maleic anhydride and aminated withaminophenyldiamine and other dispersant amines.

The third class of polymers useful in the practice of the presentinvention are acrylate or alkylacrylate copolymer derivatives havingdispersing groups (hereinafter “Polymer (iii)”). These polymers havebeen used as multifunctional dispersant viscosity modifiers inlubricating oil compositions, and lower molecular weight polymers ofthis type have been used as multifunctional dispersant/LOFIs. Suchpolymers are commercially available as, for example, ACRYLOID 954, (aproduct of RohMax USA Inc.) The acrylate or methacrylate monomers andalkyl acrylate or methacrylate monomers useful in the formation ofPolymer (iii) can be prepared from the corresponding acrylic ormethacrylic acids or their derivatives. Such acids can be derived usingwell known and conventional techniques. For example, acrylic acid can beprepared by acidic hydrolysis and dehydration of ethylene cyanohydrin orby the polymerization of β-propiolactone and the destructivedistillation of the polymer to form acrylic acid. Methacrylic acid canbe prepared by, for example, oxidizing a methyl α-alkyl vinyl ketonewith metal hypochlorites; dehydrating hydroxyisobutyric acid withphosphorus pentoxide; or hydrolyzing acetone cyanohydrin.

Alkyl acrylates or methacrylate monomers can be prepared by reacting thedesired primary alcohol with the acrylic acid or methacrylic acid in aconventional esterification catalyzed by acid, preferably p-toluenesulfonic acid and inhibited from polymerization by MEHQ or hydroquinone.Suitable alkyl acrylates or alkyl methacrylates contain from about 1 toabout 30 carbon atoms in the alkyl carbon chain. Typical examples ofstarting alcohols include methyl alcohol, ethyl alcohol, ethyl alcohol,butyl alcohol, octyl alcohol, iso-octyl alcohol, isodecyl alcohol,undecyl alcohol, dodecyl alcohol, tridecyl alcohol, capryl alcohol,lauryl alcohol, myristyl alcohol, pentadecyl alcohol, palmityl alcoholand stearyl alcohol. The starting alcohol can be reacted with acrylicacid or methacrylic acid to form the desired acrylates andmethacrylates, respectively. These acrylate polymers may have numberaverage molecular weights ( Mn) of 10,000 to 1,000,000 and preferablythe molecular weight range is from about 200,000 to 600,000.

To provide an acrylate or methacrylate with a dispersing group, theacrylate or methacrylate monomer is copolymerized with anamine-containing monomer or the acrylate or methacrylate main chainpolymer is provided so as to contain sights suitable for grafting andthen amine-containing branches are grafted onto the main chain bypolymerizing amine-containing monomers.

Examples of amine-containing monomers include the basic aminosubstituted olefins such as p-(2-diethylaminoethyl) styrene; basicnitrogen-containing heterocycles having a polymerizable ethylenicallyunsaturated substituent such as the vinyl pyridines or the vinylpyrrolidones; esters of amino alcohols with unsaturated carboxylic acidssuch as dimethylaminoethyl methacrylate and polymerizable unsaturatedbasic amines such as allyl amine.

Preferred Polymer (iii) materials include polymethacrylate copolymersmade from a blend of alcohols with the average carbon number of theester between 8 and 12 containing between 0.1-0.4% nitrogen by weight.

Most preferred are polymethacrylate copolymers made from a blend ofalcohols with the average carbon number of the ester between 9 and 10containing between 0.2-0.25% nitrogen by weight provided in the form ofN—N Dimethylaminoalkyl-methacrylate.

Lubricating oil compositions useful in the practice of the presentinvention contain Polymer (i), (ii), (iii), or a mixture thereof, in anamount of from about 0.10 to about 2 wt. %, based on polymer weight;more preferably from about 0.2 to about 1 wt. %, most preferably fromabout 0.3 to about 0.8 wt. %. Alternatively in discussing themultifunctional components; specifically Polymers (ii) and (iii); saidcomponents are present providing nitrogen content to the lubricating oilcomposition from about 0.0001 to about 0.02 wt. %, preferably from about0.0002 to about 0.01 wt. %, most preferably from about 0.0003 to about0.008 wt. % of nitrogen. Polymers (i), (ii) (iii) and mixtures thereofneed not comprise the sole VM and/or LOFI in the lubricating oilcomposition, and other VM, such as non-functionalized olefin copolymerVM and, for example, alkylfumarate/vinyl acetate copolymer LOFIs may beused in combination therewith. For example, a heavy duty diesel engineof the present invention may be lubricated with a lubricating oilcomposition wherein the high molecular weight polymer is a mixturecomprising from about 10 to about 90 wt. % of a hydrogenatedstyrene-isoprene block copolymer, and from about 10 to about 90 wt. %non-functionalized OCP.

In the present invention it may be necessary to include an additivewhich maintains the stability of the viscosity of the blend. Thus,although polar group-containing additives achieve a suitably lowviscosity in the pre-blending stage it has been observed that somecompositions increase in viscosity when stored for prolonged periods.Additives which are effective in controlling this viscosity increaseinclude the long chain hydrocarbons functionalized by reaction withmono- or dicarboxylic acids or anhydrides which are used in thepreparation of the ashless dispersants as hereinbefore disclosed.

When lubricating compositions contain one or more of the above-mentionedadditives, each additive is typically blended into the base oil in anamount that enables the additive to provide its desired function.

When lubricating compositions contain one or more of the above-mentionedadditives, each additive is typically blended into the base oil in anamount that enables the additive to provide its desired function.Representative effect amounts of such additives, when used in crankcaselubricants, are listed below. All the values listed are stated as masspercent active ingredient.

TABLE II MASS % MASS % ADDITIVE (Broad) (Preferred) Metal Detergents0.1-15  0.2-9   Corrosion Inhibitor 0-5 0-1.5 Metal DihydrocarbylDithiophosphate 0.1-6   0.1-4   Antioxidant 0-5 0.01-3    Pour PointDepressant 0.01-5   0.01-1.5  Antifoaming Agent 0-5 0.001-0.15 Supplemental Antiwear Agents   0-1.0 0-0.5 Friction Modifier 0-5 0-1.5Viscosity Modifier 0.01-10   0.25-3    Basestock Balance Balance

Fully formulated lubricating oil compositions of the present inventionpreferably have a sulfur content of less than about 0.4 mass %, moreless than about 0.35 mass % more preferably less than about 0.03 mass %,such as less than about 0.15 mass %. Preferably, the Noack volatility ofthe fully formulated lubricating oil composition (oil of lubricatingviscosity plus all additives) will be no greater than 13, such as nogreater than 12, preferably no greater than 10. Fully formulatedlubricating oil compositions of the present invention preferably have nogreater than 1200 ppm of phosphorus, such as no greater than 1000 ppm ofphosphorus, or no greater than 800 ppm of phosphorus. Fully formulatedlubricating oil compositions of the present invention preferably have asulfated ash (SASH) content of about 1.0 mass % or less.

It may be desirable, although not essential to prepare one or moreadditive concentrates comprising additives (concentrates sometimes beingreferred to as additive packages) whereby several additives can be addedsimultaneously to the oil to form the lubricating oil composition. Aconcentration for the preparation of a lubricating oil composition ofthe present invention may, for example, contain from about 0.15 to about20 mass % of a compound of Formula (II); about 10 to about 40 mass % ofa nitrogen-containing dispersant; about 2 to about 20 mass % of anaminic antioxidant, a phenolic antioxidant, a molybdenum compound, or amixture thereof; about 5 to 40 mass % of a detergent; and from about 2to about 20 mass % of a metal dihydrocarbyl dithiophosphate.

The final composition may employ from 5 to 25 mass %, preferably 5 to 18mass %, typically 10 to 15 mass % of the concentrate, the remainderbeing oil of lubricating viscosity and viscosity modifier.

All weight (and mass) percents expressed herein (unless otherwiseindicated) are based on active ingredient (A.I.) content of theadditive, and/or upon the total weight of any additive-package, orformulation which will be the sum of the A.I. weight of each additiveplus the weight of total oil or diluent.

This invention will be further understood by reference to the followingexamples, wherein all parts are parts by weight, unless otherwise noted.

EXAMPLES Synthesis Example 1 Preparation of 2-(2-naphthyloxy)ethanol byethoxylation of 2-naphthol with ethylene carbonate

A two-liter resin kettle equipped with a mechanical stirrer,condenser/Dean-Stark trap, and inlets for nitrogen, was charged with2-naphthol (600 g, 4.16 moles), ethylene carbonate (372 g, 4.22 moles)and the mixture was heated to 90° C. under nitrogen. Aqueous sodiumhydroxide (50 wt %, 3.0 g) was added and the reaction mixture was heatedslowly to 165° C. The reaction mixture was kept at 165° C. for twohours. CO₂ evolved as the reaction progressed. The reaction was nearcompletion when the evolution of CO₂ ceased. The product was collectedand solidified while cooling to room temperature. The completion ofreaction was confirmed by GC, FT-IR and HPLC. The structure of theproduct was confirmed by 1H and 13C-NMR and Mass spectra (FDMS).

Synthesis Example 2 Preparation of poly (2-methoxynaphthalene-co-2-(2-naphthyloxy)ethanol-alt co-formaldehyde) bypolymerization of 2-methoxy naphthalene and 2-(2-naphthyloxy)ethanolwith formaldehyde

A two-liter resin kettle equipped with a mechanical stirrer,condenser/Dean-Stark trap, and inlets for nitrogen, was charged with2-(2-naphthyloxy)ethanol from example 1 (131.6 g), 2-methoxy naphthalene(47.4 g), toluene (50 g), and sulfonic acid (6.0 g), and the mixture washeated to 70° C. under nitrogen. Para-formaldehyde (31.57 g) was addedover 15 min at 70-80° C., and heated to 90° C. and the reaction mixturewas kept at that temperature for 30 minutes to one hour. The temperaturewas gradually increased to 110° C. to 120° C. over two to three hoursand water (75-83 ml) was removed by azeotropic distillation. The polymerwas collected and solidified while cooling to room temperature. Mn wasdetermined by GPC using polystyrene standard corrected with the elutionvolume of 2-(2-naphthyloxy)ethanol as internal standard. THF was used aseluent. Mn was 1000 dalton. 1H and 13C NMR confirmed the structure. FDMSand MALDI-TOF indicated that the product contained a mixture of oligomerfrom dimer to twenty four-mer and some side reaction products of poly(2-methoxy naphthalene-alt-co-formaldehyde) and poly(2-(2-naphthyloxy)ethanol-alt-co-formaldehyde).

Synthesis Example 3 Reaction Product of PIB-Succinic Anhydride andProduct of Synthesis Example 2

A five-liter resin kettle equipped with mechanical stirrer,condenser/Dean-Stark trap, inlets for nitrogen, and additional funnelwas charged with the products mixture from Synthesis Example 2, toluene(50-100 g) and the mixture was heated to 120° C. under nitrogen.PIB—succinic anhydride (Mn: 450 (PIB), 408 g) was added portion wise(˜25 g at 30 min intervals) and the temperature was kept at 120° C. fortwo hours followed by heating to 140° C. under nitrogen purge for anadditional two hours to strip off all solvents to a constant weight.Base oil (AMEXOM 100 N, 332 g) was added, and the product was collectedat room temperature. GPC and FT-IR confirmed the desired structure.

The reaction scheme for the above-synthesis is shown below:

Lubricant samples formulated with a conventional heavy duty diesel(PC-10 or API CI-4) additive package (containing dispersant, detergent,ZDDP antiwear agent, ashless antioxidant and PIBSA); viscosity modifier(VM); flow improver (LOFI); and base oil with and without the inventivecompound of Synthesis Example 3 were formed as follows:

TABLE III Example 1 Example 2 Example 3 (comp.) (inv.) (inv.) (mass %)(mass %) (mass %) Additive Package 17.60 17.60 17.60 Grp. II Base Oil74.82 74.82 73.34 VM 5.90 5.90 5.90 LOFI 0.20 0.20 0.20 Synthesis Ex. 3— 1.48 2.96 Compound 100.00 100.00 100.00

The soot dispersing performance of Examples 1 to 3 was evaluated in theCarbon Black Bench Test (CBBT), In the carbon black bench test, finishedoils are evaluated for their ability to disperse carbon black. Thefinished oil is mixed with the desired amount of carbon black, stirredovernight at 90° C., and evaluated using a rotational viscometer forviscosity and index. The shear rate of the rotational viscometer isvaried up to 300 sec⁻¹ and a plot of shear versus log viscosity isobtained. If the viscosity is Newtonian, the slope of the plot (index)approaches unity indicating that the soot is well-dispersed. If theindex becomes significantly less than unity, there is shear thinningindicative of poor soot dispersancy. In addition to the index, theviscosity of the oil at low shear becomes thicker as the ability of thelubricant to disperse the soot decreases, Table IV shows the results ofthe comparison in terms of index, while Table V shows the results of thecomparison in terms viscosity.

TABLE IV Index % Carbon Example 1 Example 2 Example 3 Black (comp.)(inv.) (inv.) 0 0.994 0.999 0.999 6 0.816 0.982 0.986 8 0.282 0.9790.983 12 TVTM* 0.670 0.968 *too viscous to measure

TABLE V Viscosity (cP) % Carbon Example 1 Example 2 Example 3 Black(comp.) (inv.) (inv.) 0 12.33 12.93 13.20 6 36.64 28.79 27.28 8 167.4932.70 34.41 12 TVTM 138.43 71.10

As is shown, the presence of the soot dispersing compound providesimproved index and viscosity at higher levels of carbon black versus thelubricant formulated without the compound.

The disclosures of all patents, articles and other materials describedherein are hereby incorporated, in their entirety, into thisspecification by reference. A description of a composition comprising,consisting of, or consisting essentially of multiple specifiedcomponents, as presented herein and in the appended claims, should beconstrued to also encompass compositions made by admixing said multiplespecified components. The principles, preferred embodiments and modes ofoperation of the present invention have been described in the foregoingspecification. What applicants submit is their invention, however, isnot to be construed as limited to the particular embodiments disclosed,since the disclosed embodiments are regarded as illustrative rather thanlimiting. Changes may be made by those skilled in the art withoutdeparting from the spirit of the invention.

1. Compounds of the formula:

wherein: each Ar independently represents an aromatic moiety having 0 to3 substituents selected from the group consisting of alkyl, alkoxy,alkoxyalkyl, aryloxy, aryloxyalkyl, hydroxy, hydroxyalkyl, halo andcombinations thereof; each L is independently a linking moietycomprising a carbon-carbon single bond or a linking group; each Y is—OR″ wherein each R″ is independently selected from C₁ to C₁₀₀ alkyl andaryl; each a is independently 0 to 3, with the proviso that at least oneAr moiety bears at least one group Y; and m is 1 to
 100. 2. Compounds ofclaim 1, wherein m is 2 to
 100. 3. Compounds of the formula:

wherein: each Ar independently represents an aromatic moiety having 0 to3 substituents selected from the group consisting of alkyl, alkoxy,alkoxyalkyl, aryloxy, aryloxyalkyl, hydroxy, hydroxyalkyl, halo andcombinations thereof; each L is independently a linking moietycomprising a carbon-carbon single bond or a linking group; from about 2%to about 98% of the Y units are each independently —OR″; and from about98% to about 2% of the Y units are one or more moiety of the formulaH(O(CR₂)_(n))_(y)X—, wherein X is selected from the group consisting of(CR′₂)_(z), O and S; R and R′ are each independently selected from H, C₁to C₆ alkyl and aryl; R″ is selected from C₁ to C₁₀₀ alkyl and aryl; zis 1 to 10; n is 0 to 10 when X is (CR′₂)_(z), and 2 to 10 when X is Oor S; and y is 1 to 30; each a is independently 0 to 3, with the provisothat at least one Ar moiety bears at least one group Y; and m is 1 to100.
 4. Compounds of claim 3, wherein m is 2 to
 100. 5. Compounds ofclaim 3, wherein from about 2% to about 98% of Y units areH(O(CR₂)₂)_(y)O—, wherein y is 1 to 6, and from about 98% to 2% of Yunits are —OR″.
 6. Compounds of claim 5, wherein Ar is naphthalene; fromabout 40% to about 90% of Y units are HOCH₂CH₂O—, and from about 90% to10% of Y units are —OCH₃; and L is CH₂.
 7. Compounds of claim 6, whereinfrom about 65 mol. % to about 75 mol. % of Y units are HOCH₂CH₂O—, andfrom about 35 mol. % to about 25 mol. % of Y units are —OCH₃. 8.Compounds of claim 7 derived from about 65 mol. % to about 75 mol. % of2-(2-naphthoxy)-ethanol and from about 35 mol. % to about 25 mol. ° A)of 2-methoxy naphthalene, wherein m is 1 to about
 25. 9. A process forforming compounds, or mixtures of compounds, of claim 8 comprisingreaction of naphthyloxyethanol and 2-methoxylnaphthalene withformaldehyde in the presence of an acid.
 10. The process of claim 9,wherein naphthoxyethanol is the product of a process comprising reactionof a hydroxyl-naphthylene compound with ethylene carbonate in thepresence of a base catalyst.
 11. The process of claim 10, whereinremaining base is neutralized with an excess of acid prior tointroduction of said formaldehyde.
 12. The process of claim 11, whereinsaid acid is selected from oil soluble sulfonic acid and solid acidcatalyst.
 13. A reaction product of one or more compounds as claimed inclaim 1, and an acylating agent.
 14. The reaction product of claim 13,wherein said acylating agent is at least one selected from polyalkylsuccinic acylating agent and polyalkenyl succinic acylating agentderived from polyalkene having Mn of from about 100 to about
 5000. 15.The reaction product of claim 13, wherein said acylating agent ishydrocarbyl isocyanate.
 16. A reaction product of one or more compoundsas claimed in claim 2, and an acylating agent.
 17. The reaction productof claim 16, wherein said acylating agent is at least one selected frompolyalkyl succinic acylating agent and polyalkenyl succinic acylatingagent derived from polyalkene having Mn of from about 100 to about 5000.18. The reaction product of claim 16, wherein said acylating agent ishydrocarbyl isocyanate.
 19. The reaction product of a mixture ofmethylene-bridged naphthoxyethanol and 2-methoxy naphthalene compounds,and an acylating agent selected from polyalkyl succinic acylating agentand polyalkenyl succinic acylating agent.
 20. A process for forming theproduct of claim 19, wherein said mixture of methylene-bridgednaphthoxyethanol and 2-methoxy naphthalene compounds, and acylatingagent are reacted in the presence of an acid catalyst.
 21. The processof claim 20, wherein said methylene-bridged naphthoxyethanol and2-methoxy naphthalene compounds are the products of a process comprising(i) reacting hydroxyl-naphthalene compound and ethylene carbonate in thepresence of a base catalyst to form naphthyloxyethanol; (ii)neutralizing said base with an excess of acid to provide anintermediate; and (iii) reacting said intermediate with 2-methoxynaphthalene and formaldehyde in the presence of residual acid.
 22. Theprocess of claim 21, wherein said acid is selected from oil solubleliquid acid catalyst and solid acid catalyst.
 23. The process of claim22, wherein said acylating agent is polybutenyl succininc acylatingagent derived from polybutene having Mn of from about 300 to about 5000.24. The process of claim 23, wherein a ratio of total moles of succinicacylating moieties to total moles of naphthyl moieties of saidnaphthyloxyethanol and said 2-methoxy naphthalene is from about 1.10 toabout 0.5.